1. Field of the Invention
The present invention relates to a charge coupled transfer arrangement in which majority carriers are used for the charge transfer, in particular according to the peristaltic principle or according to the buried channel principle for the storage and movement of electrical charges in a predetermined direction, and more particularly to a charge coupled transfer arrangement which comprises a thin doped semiconductor layer on material which is highly resistive with respect to the semiconductor layer, and a layer consisting of insulating material arranged on the semiconductor layer on which insulation are disposed means for feeding the charges, several individual electrode arrangements disposed in a row parallel to the given direction to serve for movement of the charges, and means for removing the charges.
2. Description of the Prior Art
Transfer arrangements of the initially mentioned type are known in the art and are described, for example, by L. J. M. Esser in his article Peristaltic CCD: A New Type of Charge Transfer Device, in the periodical Electronics Letters Dec. 14, 1972, Vo. 8, No. 25, Pages 620-621, in the German published applicaton 2,252,148, and by R. H. Walden in his article The Buried Channel CCD, in the Bell System Technical Journal, Vol. 51, Sept. 1972, No. 7, Pages 1635-1640. Such arrangements consist of a thin doped semiconductor layer on material which is highly resistive in relation thereto, and a layer consisting of insulating material arranged on the semiconductor layer. The insulating layer carries means for feeding in charges, several individual electrodes for moving the charges, which are arranged in a row parallel to a predetermined transfer direction, and output means for removing the charges. During production, one proceeds from an epitaxial layer on a high resistive semiconductor body. Voltage pulses are applied to the electrodes as is done with the conventional charge coupled element.
The primary different between this type of element and the conventional element resides in the fact that the charge transfer takes place primarily in the interior of the semiconductor layer and that majority charge carriers are used for the charge transfer.
The transfer of the charge from one electrode to the next electrode takes place in such a way that by means of applying appropriate amounts of voltages to the electrodes, the cross section of the current carrying portion in the semiconductor layer is changed. For example, if the current carrying cross section below an electrode is reduced, and if it is expanded at the same time at an adjacent electrode, the current then flows to the adjacent electrode. When sufficiently high voltages are applied to an electrode, the current carrying cross section becomes infinitely small, i.e. the entire semiconductor below the electrode is practically free of majority carriers. The entire charge is then located below an adjacent electrode. Transfer arrangements of the type mentioned above are characterized by particularly favorable electrical features, among other things, by small tranfer losses and high transfer frequencies.
However, the charge movement from one electrode to the next can function in transfer arrangements of the initially mentioned kind only if the charge cannot flow laterally from the row of electrodes. For this reason, a transfer channel is necessary in such elements below the row of electrodes, the transfer channel being laterally insulated with respect to its surroundings. When producing this kind of transfer arrangements, this insulation, however, requires additional method steps which are not necessary with conventional elements.